Pumps



Oct. 12, 1965 s, ASHWORTH ETAL, 3,211,101

PUMPS Filed Feb. 28, 1964 United States Patent 3,211,101 PUMPS StewartIves Ashworth, Crimond, Outhill, near Studley,

and Anthony Gerard Field, Redditch, England, assignors to AbrasiveDevelopments Limited, Solihull, England, a British company Filed Feb.28, 1964, Ser. No. 348,154 Claims priority, application Great Britain,Jan. 7, 1964, 736/ 64 5 Claims. (Cl. 103-103) This invention relates topumps and more particularly to centrifugal pumps for liquid of the typein which the running joint between the impeller shaft and the impellerhousing is effected by means of a hollow cylinder of liquid in aclearance between the exterior of the shaft and the internal surface ofa sleeve through which the shaft passes.

Such pumps are used for pumping liquids containing abrasive material andtwo examples of such pumps are disclosed in British Patent No. 840,671and co-pending patent application Serial No. 262,980 filed by StewartIves Ashworth on March 5, 1963, now U.S. Patent No. 3,160,106.

In both these prior arrangements, the liquid used to make the runningjoint is the liquid which is being pumped. In the arrangement describedin British Patent No. 840,671 the liquid for the joint is drawn directlyfrom the impeller casing and is not substantially clarified, althoughblades are provided on the back face of the impeller which throw out anylarge abrasive particles in the liquid flowing towards the sleeve. Inthe arrangement described in application Serial No. 262,980, means isprovided for substantially clarifying the liquid which is to be used tomake the running joint. This means comprises a vortex chamber in which avortex is obtained by means of small blades on the back face of theimpeller. Liquid flows from the centre of the vortex up the clearancebetween the sleeve and the shaft into an overflow chamber. While thisarrangement is generally satisfactory it does have certain limitations.The secondary flow of liquid from the vortex chamber back into theimpeller housing causes undesirable turbulence within the impellerhousing and to some extent impedes the separation of abrasive from theliquid which is intended to be used as the seal within the sleeve. Afurther limitation of the arrangement described in said co-pendingapplication is that, since the vortex chamber is open to the impeller,the speed of the vortex in the vortex chamber is controlled by the speedof the impeller and cannot rotate faster than the impeller, this canimpede abrasive separation.

It is an object of the present invention to provide a centrifugal pumpfor liquid of the type in which the running joint between the impellershaft and the impeller housing is effected by means of a hollow cylinderof liquid in the clearance between the exterior of the shaft and theinternal surface of a sleeve through which the shaft passes and of whichsubstantially overcomes the above disadvantages.

According to the invention, there is provided a pump comprising animpeller housing having a central inlet and a peripheral outlet butbeing otherwise closed, a vortex chamber having a peripheral inlet andan outlet, means for connecting the outlet of the impeller housing tothe inlet of the vortex chamber, an impeller rotatable in the housing todraw liquid through the housing inlet and deliver it through the housingoutlet to said connecting means, an impeller shaft secured to theimpeller and extending therefrom through an aperture in the wall of thehousing and through the centre of the vortex chamber, and a sleevesurrounding the shaft with clearance and secured at one end to theimpeller housing around said aperture and opening at the other end inthe vortex chamber centrally thereof and in a position such that liquidflows from the centre of the vortex along the sleeve into the impellerhousing forming a liquid seal between the shaft and the sleeve.

The important distinction of the pump according to the present inventionfrom the previously proposed pumps mentioned above, is that in pumpsembodying the present invention the liquid forming the seal flows fromthe vortex chamber into the impeller housing whereas in the previouslymentioned pumps the liquid forming the seal flows out of the impellerhousing into the sleeve. In the majority of cases, the whole of theoutput of liquid from the impeller housing will be fed through thevortex chamber. Since the vortex chamber is not open to the impeller,the speed of ,the vortex in the chamber will not be retarded by theimpeller. Moreover, there will be no secondary circulation in oppositionto the main circulation. The main circulation is from the inlet of theimpeller housing centrifugally outwardly to the outlet thereof and theliquid which passes down the clearance between the sleeve and the shaftwill also move centrifugally outwardly in the impeller housing when itreaches the housing. It follows that the main flow and the auxiliarysealing flow will be in the same direction within the impeller housing.This will reduce unnecessary turbulence within the impeller housing andwill cut down the Wear in the housing.

The invention will now be described by way of example with reference tothe accompanying drawing which is a cut-away perspective view of a pumpembodying the invention.

Referring now to the drawing, the pump is arranged with its impellershaft 10 vertical and with its impeller housing 11 at the bottom of anassembly comprising the impeller housing, a vortex chamber 12 and adriving motor 13 for the pump. The vortex chamber 12 is interposedbetween the impeller 11 housing and the driving motor 13. The impellerhousing is of conventional form and is a volute with a peripheraltangential outlet 14 and an inlet 15 co-axial with the axis of the shaft10. A main impeller 16, having main vanes 17 on one face thereof, issecured to the lower end of the impeller shaft 10 for rotation withinthe housing 11, the main vanes 17 face the inlet 15. On the face of theimpeller remote from the inlet are auxiliary vanes 18 which are ofapproximately half the length of the main vanes 17 and about a quarterof their depth. In operation of the pump, the action of the auxiliaryvanes 18 oppose the action of the main vanes 17 for reasons which willbe discussed hereinafter.

The upper face 19 of the main impeller is provided with a boss 20 whichis received with clearance in an aperture 21 in the upper wall 22 of theimpeller housing. The clearance communicates with the inner ends of theauxiliary vanes 18 at its lower end and at its upper end the clearancecommunicates with the lower end of a sleeve 23 which extends upwardlyfrom the upper wall of the impeller housing. At its lower end the sleeveis formed with a flange 24 which is secured to the upper 'wall of theimpeller housing.

Secured to the exterior of the upper wall of the impeller housing 22 isthe generally cylindrical vortex chamber 12 and this surrounds, and isco-axial with the sleeve 23. The vortex chamber is closed at its lowerend by the upper wall 22 of the impeller housing and is closed at itsupper end by an annular wall 25 having a central aperture 26 thereinthrough which the shaft passes with clearance. The upper end 27 of thesleeve 23 is adjacent to but spaced below the upper wall 25 of thevortex chamber.

The vortex chamber is generally cylindrical and is of an internaldiameter substantially equal to the diameter of the impeller. The vortexchamber has 21 peripheral tangential inlet 28 adjacent its upper end andthis tangential inlet is connected by a U-tube 29 to the outlet 14 fromthe impeller housing so that all the liquid which leaves the impellerhousing passes through the U-tube into the vortex chamber. A tangentialoutlet 30 from the vortex chamber is provided adjacent to the lower endthereof.

Above the vortex chamber is provided an overflow chamber 31 which is ofa diameter equal to the vortex chamber and has a peripheral outlet 32.Mounted on the shaft 10 within the overflow chamber is a fourbladedscavenging impeller 33. The upper wall 34 of the overflow chamber isannular and the aperture 35 in said wall is of greater diameter than thescavenging impeller 33. At the top of the overflow chamber is a flange36 to which the lower end of a conical sleeve 37 supporting the motor isbolted. Ventilation openings 38 are p ovided in the peripheral wall ofthe overflow chamber above the wall 34. The impeller housing 11 isprovided with a rubber lining indicated at 39 and the main impeller isalso covered with rubber.

The operation of the pump is as follows, as the motor 13 is energised,it will rotate the shaft 10 thus rotating the scavenging impeller 33 inthe overflow chamber 31 and the main impeller 16 in the impeller housing11. Liquid containing abrasive will be drawn into the inlet of theimpeller housing and will be flung outwardly by the main vanes 17 of theimpeller and will move outwardly in the volute and out of the tangentialoutlet 14. The liquid will then pass aroundthe U-tube 29 into the inlet28 to the vortex chamber 12. Since the inlet 28 to the vortex chamber.is tangential, the liquid in the vortex chamber will swirl around thechamber in the form of a vortex having the sleeve 23 at the centrethereof and will then flow out of the chamber through the outlet 30 atthe bottom thereof.

A substantial clearance is left between the exterior of the shaft 10 andthe internal surface of the sleeve 23 and liquid from the centre of thevortex passes down this clearance into the impeller housing 11. Thevortex is such that the majority of any abrasive particles carried inthe liquid are flung to the outer wall of the vortex chamber and passthrough the outlet 30 thereof. The inner core of the vortex will consistof substantially clear liquid and it is this clear liquid which passesdown the clearance to form the'running joint between the shaft 10 andthe sleeve 23.

The liquid in the vortex is forced to whirl in circles of decreasingdiameter which not only separates the abrasive from the liquid asmentioned above but also generates by centrifugal action a back pressurewhich is only a little less than the pressure of the liquid dischargedfrom the impeller housing." This back pressure effectively regulates theflow of liquid through the clearance between the shaft 10 and the sleeve23. The upper end 27 of the sleeve is so positioned, relative to theinlet to the vortex chamber and to the upper wall thereof, that it willlie in the central column of clear liquid of the vortex and will not beexposed to air.

Some of this clear liquid will, unavoidably flow through the aperture 26in the upper wall of the vortex chamber into the overflow chamber 31.The scavenging impeller '33 in the overflow chamber effectively.prevents the liquid flowing further up the shaft into the motor and thebearings thereof and the blades of the scavenging impeller 33 fling theliquid .in the overflow chamber to the outer wall thereof so that theliquid passes through the outlet 32.

The auxiliary vanes 18 on the upper face of the impeller oppose the mainvanes 17 and thus maintain the necessary pressure difference for theclear liquid to pass down the clearance between the sleeve 23 and theshaft 10 and enter the impeller housing.

The exterior of the shaft is given a smooth finish so as to eliminate,so far as possible, secondary whirl of the liquid in the clearance andthis liquid helps to reduce vibration of the long impeller shaft.

The arrangement described has the advantages enumerated above that theflow of the sealing liquid is substantially free from abrasive particleswhich cause unnecessary wear. Moreover, since the vortex chamber is notin communication with the impeller, there is no brake on the speed ofwhirl of the vortex in the chamber. It is thus possible to obtain veryefficient separation of the abrasive from the liquid.

The liquid discharged from the overflow chamber may be returned to theinlet of the pump or otherwise disposed of. In the embodiment describedwhere all the liquid discharged from the impeller housing passes throughthe vortex chamber, the effective outlet of the pump is the outlet 30from the vortex chamber. In an alternative arrangement it would bepossible to pass a substantial part of the output from the impellerhousing through the vortex chamber and to take the remainder of theoutput directly from the impeller housing.

What we claim then is:

1. A pump comprising, an impeller housing having a central inlet and aperipheral outlet but being otherwise closed, a vortex chamber having aperipheral inlet and an outlet, means for connecting the outlet of theimpeller housing to the inlet of the vortex chamber, an impellerrotatable in the housing to draw liquid through the housing inlet anddeliver it through the housing outlet to said connecting means andimpeller shaft secured to the impeller and extending therefrom throughan aperture in the wall of the housing and through the centre of thevortex chamber, and a sleeve surrounding the shaft with clearance andsecured at one end to the impeller housing around said aperture andopening at the other end in the vortex chamber centrally thereof and ina'position such that liquid flows from the centre of the vortex alongthe sleeve into the impeller housing forming a liquid seal between theshaft and the sleeve.

2. A pump as claimed in claim 1, including main and auxiliary vanes onthe impeller, the main vanes facing the inlet of the housing to impelliquid from said inlet to the outlet of the housing and the auxiliaryvanes facing said aperture to assist flow of liquid from the chamber tothe housing through the sleeve.

3. A pump as claimed in claim 1, including means for securing one end ofthe vortex chamber to the impeller housing so that the chamber andhousing'are co-axial, and wherein the outlet from the chamber isadjacent said one end and the inlet to said chamber is adjacent to theend of the chamber remote from said one end.

4. A pump as claimed in claim 3, including an overflow chamber at saidremote end of the vortex chamber, said overflow chamber communicatingwith the vortex chamber through a clearance surrounding the shaft, anddeflector 'means on'the shaft in the overflow chamber to prevent liquidflowing along the shaft past the deflector means.

5. A pump as claimed in claim 4including a bladed impeller forming partof said deflector means to direct 5 6 liquid flowing along the shaft tothe periphery of the FOREIGN PATENTS over'fiowchamber- 304,763 8/17Germany.

References Cited by the Examiner OTHER REFERENCES UNITED STATES PATENTS5 Van Gerfsheim, German printed application No. 1,642,914 9/27 Whann103102 1,155,677,10/63. 2,930,325 3/60 Beard et a1. 103103 3,160,10612/64 Ashworth 103- 103 DONLEY J. STOCKING, Primary Examiner.

1. A PUMP COMPRISING, AN IMPELLER HOUSING HAVING A CENTRAL INLET AND APERIPHERAL OUTLET BUT BEING OTHERWISE CLOSED, A VORTEX CHAMBER HAVING APERIPHERAL INLET AND AN OUTLET, MEANS FOR CONNECTING THE OUTLET OF THEIMPELLER HOUSING TO THE INLET OF THE VORTEX CHAMBER, AN IMPELLERROTATABLE IN THE HOUSING TO DRAW LIQUID THROUGH THE HOUSING INLET ANDDELIVER IT THROUGH THE HOUSING OUTLET TO SAID CONNECTING MEANS ANDIMPELLER SHAFT SECURED TO THE IMPELLER AND EXTENDING THEREFROM THROUGHAND APERTURE IN THE WALL OF THE HOUSING AND THROUGH THE CENTER OF THEVORTEX CHAMBER, AND A SLEEVE SURROUNDING THE SHAFT WITH CLEARANCE ANDSECURED AT ONE END TO THE IMPELLER HOUSING AROUND SAID APERTURE ANDOPENING AT THE OTHER END IN THE VORTEX CHAMBER CENTRALLY THEREOF AND INA POSITION SUCH THAT LIQUID FLOWS FROM THE CENTRE OF THE VORTEX ALONGTHE SLEEVE INTO THE IMPELLER HOUSING FORMING A LIQUID SEAL BETWEEN THESHAFT AND THE SLEEVE.